Onsen tamago is a simple Japanese dish, but you may not be able to make an authentic version of it at home. They're eggs slowly cooked in nature's crockpot--a hot spring:

Hot springs or "onsen," dot volcanic Japan from tip to tip (dipping into a steaming onsen one of the great pleasures of visiting Japan), and a custom for cooking eggs at these springs evolved over the years -- toss them into the hot water, wait a bit, and the egg magically poaches. The secret is the onsen's water temperature, which causes the egg's yolk and albumen congeal into a nice sphere on the outside, and beautifully creamy and tasty on the inside.